Private sewage systems still under par

Cayman’s worst performing private sewage treatment systems have made some marked improvements, but the majority still do not meet the legal standard of quality, according to tests run by the Water Authority.

Of 18 private wastewater systems with the worst results in 2008 and 2009, subsequent samplings show 12 still fall below the legal minimum standard of either biochemical oxygen demand

(BOD) or total suspended solids (TSS) – systems of testing the quality of treated sewage – or both.

One of the 18 aerobic treatment units retested met the BOD standard but its TSS results were nonreportable due to quality control issues with sampling or analysis; four have not been resampled; and only one, at CUC, was found now to be well within the legal standard of both BOD and TSS levels. However, of those dozen sites that still fell below the legal standards, most showed improved results.

One of the sites where the wastewater was not resampled was at government housing in Windsor Park where results from January 2009 showed levels were at 859.5 parts per million for BOD and 1,071.2 parts per million for TSS. That site was not resampled because the government plans to demolish the site and rehouse residents elsewhere.

The worst system recorded in 2008 tests – Georgian Courts Villas in George Town district, which at the time was more than 800 times more than the legal maximum levels of TSS showed vastly improved results when it was retested in February this year with its TSS levels falling well within the legal limit to 15.9 parts per million, compared to 8,240 parts per million three years ago. Its BOD results fell from 3,144 parts per million to 38.5 parts per million.

Both total suspended solids and biochemical oxygen demand should be 30 parts per million, according to the Water Authority Law.

Catherine Crabb of the Water Authority said the most recent data showed “marked improvements which can be attributed to owners obtaining the required service … The results are encouraging as they illustrate to owners the effectiveness of service.”

Since being tested in 2008 and 2009, some sites improved to the point where they met the legal standard for a while, but then a lack of maintenance led them again to fail sampling tests taken this year.

Ms Crabb said that “to ensure we don’t just create a cycle of system neglected, poor sample results shock, service obtained, results improve, system neglected … repeat cycle,” a system needed to be established that would require service contracts for routine maintenance and not just corrective or emergency service.

“To that end, we are working with service providers to raise the standard of service provided,” she said.

The Water Authority is running an onsite wastewater management programme for owners of private sewerage systems, which urges the use of a standard service report document for work carried by service providers on the systems.

The Authority is also encouraging sewage system service providers to take basic proficiency tests set.

The Water Authority has tested all 448 aerobic treatment systems on the island installed before August 2010 at least once. Of those, 91 per cent failed the BOD and/or TSS effluent limits.

Those systems on private property treat 25 per cent of the sewage in Cayman. There are also 15,000 septic tanks treating 60 per cent of the flows generated. The remaining sewage is treated by a public sewage treatment system.

“We are looking for and considering equipment/measures that can be taken to improve the performance of these [septic tanks] short of requiring that they all be replaced with aerobic treatment units which … have their own set of challenges,” said Ms Crabb. Under the law, the Water Authority can prosecute owners who fail to ensure their waste systems are up to the required legal standards. Ms Crabb said: “At this stage in the programme, our objective is to advise all onsite wastewater management partners of their role and responsibilities and to provide them with the information they need to carry out those responsibilities. Enforcement actions are not taken at this stage until and unless a system poses an immediate risk to public health or the environment, or when insufficient efforts are being made to achieve compliance.”

She said that since the programme began, several failing systems had been repaired, upgraded or replaced at sites throughout Cayman, including at Owen Roberts Apartment complex, Templeton Pines Apartment complex, Madison Place (formerly Señor Frog’s, and Mango Tree.

“We are currently working with the strata of Fountain Court to address chronic complaints regarding their system,” she said.

Although the Water Authority can take legal enforcement action against owners of defective wastewater systems, no owner has yet been prosecuted for failing to meet the legal standard of quality.

However, the Authority has recommended to the Ministry of District Administration, Works, Lands and Agriculture that enforcement action be taken against the strata of Randyke Gardens, a site that has raised concerns over the years due to its low quality of treated wastewater.

Ms Crabb said the site posed an immediate risk to public health and the environment, which was caused by insufficient efforts being made to meet the legal quality standards.

“This is very discouraging as the crisis situation at Randyke Gardens in 2006 and 2007 … was the case that served to raise the attention of government and agencies that greater oversight and accountability was required to manage these systems. Given the immediacy of the problem and the lack of the strata having adequate management structure or funds, government advanced the funds to replace the failed systems with brand new systems – NSF-certified engineered systems whose installation was overseen and signed off by the Water Authority. The responsibility and guidelines for ongoing maintenance were clearly communicated to the strata,” she said. However, the strata again failed to fund the required service and the systems backed up and overflowed onto the ground, Ms Crabb said.

“The Water Authority documented the saga and put it forward to the Ministry [of District Administration, Works, Lands and Agriculture] recommending enforcement. The Water Authority was directed to obtain quotes for repair and ongoing maintenance. Those quotes and the matter are currently with the ministry,” Ms Crabb said.